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Robotic nephroureterectomy in a horseshoe kidney for upper tract urothelial carcinoma
  1. Edward Ramez Latif,
  2. Issam Ahmed,
  3. Milan Thomas and
  4. Ben Eddy
  1. Urology, East Kent Hospitals University NHS Foundation Trust, Canterbury, UK
  1. Correspondence to Dr Edward Ramez Latif; elatif{at}wollemia.com.au

Abstract

Upper tract urothelial carcinoma represents a small proportion (5%–10%) of all urothelial cancers. Although there are several management options, in undifferentiated or high-risk cases, surgery in the form of nephroureterectomy is the gold standard. Horseshoe kidney is the most common congenital renal fusion anomaly affecting 1 in 400–600 patients. We present the case of a smoker in her mid-50s with an incidental finding of a papillary lesion in the right renal pelvis of her horseshoe kidney on CT scan. She went on to have endoscopic assessment confirming no other foci of disease. She was definitively managed with a robotic nephroureterectomy.

  • urology
  • urological surgery
  • surgical oncology
  • surgery
  • urological cancer

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Background

Upper tract urothelial carcinoma (UTUC) is an uncommon cancer.1 2 Its complicating feature is reduced accessibility, and thus difficulties with accurate local staging using endoscopic biopsy and endoscopic treatment. For this reason in high-risk or undifferentiated cases, radical surgery remains the standard of care.3 4

Horseshoe kidney is the most common renal fusion anomaly.5 6 It is associated with other abnormalities including pelviureteric junction obstruction, ureterocele, ectopic ureter and UTUC.7 8 Horseshoe kidneys are anatomically peculiar for their shape and position. The inferior mesenteric artery and fused isthmus limit the horseshoe kidneys’ embryological assent resulting in the kidneys being situated caudally, with the lower poles medially and anteriorly rotated. The isthmus of the kidneys is perfused and lies over the great vessels. Vascularity of the kidney is also anomalous typically with a multitude of arteries and veins being present.9 These factors add significant complexity to any surgery performed in horseshoe kidneys, particularly using a minimally invasive approach.

We present here a case of robotic nephroureterectomy in a patient with UTUC in a horseshoe kidney. Our experience shows this is a feasible approach in the carefully selected patient being operated on by a seasoned robotic surgeon. Minimally invasive surgery for this disease can be considered in selected patients presenting with UTUC in a horseshoe kidney.

Case presentation

The patient is a female in her mid-50s employed in an office environment. She is a smoker with a history of caesarean section, though no other significant medical history. She presented to her general practitioner with bloating and altered bowel habit. Her abdominal examination was unremarkable. A CT scan performed to investigate found a horseshoe kidney with a 2 cm papillary lesion in the right renal pelvis.

On referral to a urologist, she was diagnosed with a probable UTUC and further diagnostic investigations were carried out.

Investigations

Urine

Cytology: Urine cytology has high specificity but low sensitivity.10 Abnormal urine cytology mandates urinary tract assessment to exclude urothelial malignancy. While high-grade urothelial cancer and carcinoma in situ often have malignant cytology, low-grade urothelial cancer is often negative.11 Overall, urine cytology is a fairly unreliable test in the diagnosis of UTUC.12 In our patient, urine cytology was collected. The final report showed clusters of urothelial cells suspicious for low-grade urothelial cancer. Paired with the radiological and endoscopic findings, this supported the diagnosis of UTUC in the absence of biopsy.

Imaging

CT scan: CT urogram is the gold standard imaging to identify upper tract urothelial lesions.3 4 It is particularly accurate at identifying solid and papillary lesions which appear as enhancing filling defects in the collecting system. Added benefits include operative planning. In this case, the presence of abnormal anatomy and complex vasculature meant an angiographic phase was especially useful, and showed a perfused isthmus (figures 1–3). CT angiogram can show aberrant vasculature including the number of vessels to the kidney and their origin, which can include the iliac and lumbar vessels among others.9

Figure 1

The tumour is seen in the right renal pelvis (arrow). L, left; R, right.

Figure 2

The perfused isthmus crosses the aorta (arrow). L, left; R, right.

Figure 3

The CT reconstructions demonstrate the complex vascularity of the kidney.

Dimercapto succinic acid (DMSA): DMSA is a nuclear medicine test which provides accurate data regarding split renal function. It indicates whether patients undergoing nephroureterectomy will have sufficient renal function in the remaining kidney to avoid dialysis. In our patient, DMSA showed the right half of the horseshoe kidney provided 44% of total renal function and the left half 56%. Given the patient’s normal baseline renal function, this meant nephroureterectomy could be safely performed.

Invasive

Flexible ureteropyeloscopy: When planning a complex procedure such as nephroureterectomy in horseshoe kidney, visual and ideally histological confirmation is recommended, though in routine cases with enhancing urothelial mass on imaging it can be excluded to reduce risk of bladder seeding.4 Confirmation is best obtained by flexible ureteropyeloscopy. In this patient’s case, a biopsy could not be performed owing to poor access; however, the tumour was visually identified as having classic papillary architecture. In patients where nephroureterectomy is not a suitable treatment owing to conflicting priorities, such as preserving renal function or poor patient fitness, flexible pyeloscopy can facilitate treatment through laser ablation, though this is only recommended in low-grade non-invasive tumours.4

Differential diagnosis

In this patient’s case, there were no other probable diagnoses. Although rarer pathologies such as fibroepithelial polyp, fungal ball, sloughed papillae or blood clot may have accounted for the incidental finding, the clinical history effectively excluded these diagnoses. The CT had a classical appearance of UTUC, and the flexible pyeloscopy visually supported the diagnosis of papillary urothelial carcinoma.

Treatment

Following multidisciplinary team discussion, nephroureterectomy was recommended. This was performed as a robotic procedure, a previously unreported approach for this indication.

Description of the technique: The patient was placed in a left flank position with a 10° flex in the table. A DaVinci Si Surgical System robotic platform (Intuitive Surgical, Sunnyvale, CA, USA) was used with a total of four robotic ports and an additional 15 mm Air Seal iFS port (ConMed, Utica, NY, USA) infraumbilically in a right paramedian position. Three robotic ports were arranged in a linear fashion spaced approximately 15 cm apart, the fourth port was placed in a right lateral position.

The colon was medialised and the duodenum kocherised. The upper pole of the right kidney was exposed, and dissection caudally revealed the ureter and gonadal vein. The ureter was clipped distally on identification to minimise seeding. The gonadal vein was crossing the right kidney parenchyma and was divided. A unique ‘top down’ approach where dissection is carried from the upper pole of the right kidney inferiorly was used, rather than the classical approach starting at the lower pole, because the kidney was fixed in position by its isthmus with the left kidney.

This exposed the main renal artery and vein which were ligated with Weck Hem-o-lok clips (Teleflex, Morrisville, NC, USA) and divided. Further dissection along the medial aspect of the right kidney enabled the remaining several vessels previously recognised on CT angiogram to be identified and ligated. The kidney was then fully mobilised and dissection carried out to expose the left lower pole and ensure satisfactory mobility.

After folding the now devascularised right kidney to the left side of the abdomen, the great vessels were exposed and the planned renorrhaphy marked (video 1A,B). Stay sutures were placed in the left side of the renorrhaphy in anticipation of possible retraction after isthmus division. The isthmus was divided with none of the left-sided vessels exposed or clamped and as previously recognised on the CT scan the isthmus tissue was cortical in nature and perfused, not merely a fibrotic band (video 1C).

Video 1

The renorrhaphy was closed with continuous Monocryl (Ethicon, Somerville, NJ, USA) for the deep layer, followed by a sliding clip renorrhaphy closure for the superficial repair with 0 Vicryl (Ethicon). Haemostasis was confirmed and Floseal (Baxter Healthcare, Deerfield, IL, USA) applied to the exposed left side of the isthmus (video 1D). The isthmus can alternatively be divided with an energy device or linear stapler to improve haemostasis; however, in the robotic approach with pneumoperitoneum and the control offered by the robot, diathermy and ligatures are sufficient.

The ureter was then dissected into the pelvis, through the detrusor, and the mucosa of the bladder was sharply incised freeing the specimen. The bladder was then closed with two layers of continuous 0 Vicryl.

The specimen was removed through an extension of the 15 mm iFS Air Seal port site, and wounds closed in a conventional manner (figures 4 and 5).

Figure 5

The isthmus, indicated by an arrow.

Outcome and follow-up

The patient recovered in hospital for 48 hours and was mainly troubled by nausea and constipation which resolved. The drain was removed at 24 hours after the surgery. At 7 days, the urinary catheter was removed following a dose of intravesical mitomycin-C, given its benefit in reducing bladder recurrence in UTUC.13

The patient was seen at 4 weeks after surgery with histology revealing a low-grade pTa papillary urothelial carcinoma measuring 2 cm in maximum diameter, fully excised with negative surgical margins. Flexible cystoscopy at 3 months revealed no bladder urothelial carcinoma. The patient continues to follow-up as per international guidelines.

Discussion

While horseshoe kidney remains a relatively common congenital abnormality, and upper tract urothelial carcinoma a rare but not uncommon urological malignancy, they are seldom reported in the same patient in the literature.

This report describes a fully robotic nephroureterectomy performed in a patient with horseshoe kidney for upper tract urothelial carcinoma. There are previously published reports of robotic surgery for horseshoe kidney for other indications including partial nephrectomy, heminephrectomy for benign disease, pyeloplasty and pyelolithotomy.14–19 It is important that knowledge is shared regarding operative techniques, especially in the case of common congenital malformations, as it is reasonably expected that other surgeons will face similar pathologies in such patients. In this era of increasing utilisation of robotic surgery for all manner of urological malignancies, it is especially important that points of technique for minimally invasive surgery are shared.

Unique features of this procedure include the abnormal position of the vasculature, the presence of several arteries and veins to each side of the kidney, and the fact that the isthmus was perfused by the left renal vasculature. This is an especially important point because it must be recognised that this step of the surgery carries a high-bleeding risk, as it is effectively an off-clamp partial nephrectomy. It also raises the question of whether or not to dissect out the left renal vasculature, enabling clamping during isthmus division.

In our opinion this is unnecessary given the complexity of accessing the left kidney with the patient in a left side down position, the perceived increased risk of Inferior Mesenteric Artery and Superior Mesenteric Artery injury, but also because the robotic approach does allow prompt closure of the renal defect, and the pneumoperitoneum can provide some tamponade. Of course, each case should be assessed on its individual merit, and consideration given to the thickness and perfusion of the isthmus as well as the experience of the surgeon. We believe the technique described above to be a feasible and reproducible one in the hands of experienced upper tract robotic surgeons.

Learning points

  • Robotic surgery for horseshoe kidney is a feasible and viable option based on our experience. This case demonstrates that nephroureterectomy for upper tract urothelial carcinoma (UTUC) in horseshoe kidney can be performed entirely robotically.

  • The isthmus is not always a fibrotic band and its division should be treated with the same respect as an unclamped partial nephrectomy

  • An experienced bedside assistant is paramount in any such complex operation.

  • CT angiogram is invaluable in defining the invariably complex vasculature of a horseshoe kidney and is a must before embarking on surgery.

  • Renal pelvis access with flexible ureteroscopy may not be possible due to anatomical factors including the course of the ureter, limiting treatment options.

Ethics statements

References

Footnotes

  • Contributors ERL: wrote the case report; acquired patient consent and made the video and provided the voiceover. IA: helped with references and images. MT: rewrote the discussion. BE: performed the surgery; rewrote the description of the procedure performed.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.